From 4e415b4164551e712643e9608d8813cc749fd279 Mon Sep 17 00:00:00 2001 From: Peter Korsgaard Date: Tue, 21 Sep 2021 21:16:50 +0200 Subject: [PATCH] package/ghostscript: add upstream security patch for CVE-2021-3781 The file access protection built into Ghostscript proved insufficient for the "%pipe%" PostScript device, when combined with Ghostscript's requirement to be able to create and control temporary files in the conventional temporary file directories (for example, "/tmp" or "/temp). This exploit is restricted to Unix-like systems (i.e., it doesn't affect Windows). The most severe claimed results are only feasible if the exploit is run as a "high privilege" user (root/superuser level) \u2013 a practice we would discourage under any circumstances. For more details, see the advisory: https://ghostscript.com/CVE-2021-3781.html Signed-off-by: Peter Korsgaard Signed-off-by: Arnout Vandecappelle (Essensium/Mind) --- ...de-device-specifier-strings-in-acces.patch | 234 ++++++++++++++++++ package/ghostscript/ghostscript.mk | 3 + 2 files changed, 237 insertions(+) create mode 100644 package/ghostscript/0002-Bug-704342-Include-device-specifier-strings-in-acces.patch diff --git a/package/ghostscript/0002-Bug-704342-Include-device-specifier-strings-in-acces.patch b/package/ghostscript/0002-Bug-704342-Include-device-specifier-strings-in-acces.patch new file mode 100644 index 0000000000..81436d8228 --- /dev/null +++ b/package/ghostscript/0002-Bug-704342-Include-device-specifier-strings-in-acces.patch @@ -0,0 +1,234 @@ +From a9bd3dec9fde03327a4a2c69dad1036bf9632e20 Mon Sep 17 00:00:00 2001 +From: Chris Liddell +Date: Tue, 7 Sep 2021 20:36:12 +0100 +Subject: [PATCH] Bug 704342: Include device specifier strings in access + validation + +for the "%pipe%", %handle%" and %printer% io devices. + +We previously validated only the part after the "%pipe%" Postscript device +specifier, but this proved insufficient. + +This rebuilds the original file name string, and validates it complete. The +slight complication for "%pipe%" is it can be reached implicitly using +"|" so we have to check both prefixes. + +Addresses CVE-2021-3781 + +Signed-off-by: Peter Korsgaard +--- + base/gdevpipe.c | 22 +++++++++++++++- + base/gp_mshdl.c | 11 +++++++- + base/gp_msprn.c | 10 ++++++- + base/gp_os2pr.c | 13 +++++++++- + base/gslibctx.c | 69 ++++++++++--------------------------------------- + 5 files changed, 65 insertions(+), 60 deletions(-) + +diff --git a/base/gdevpipe.c b/base/gdevpipe.c +index 96d71f5d8..5bdc485be 100644 +--- a/base/gdevpipe.c ++++ b/base/gdevpipe.c +@@ -72,8 +72,28 @@ pipe_fopen(gx_io_device * iodev, const char *fname, const char *access, + #else + gs_lib_ctx_t *ctx = mem->gs_lib_ctx; + gs_fs_list_t *fs = ctx->core->fs; ++ /* The pipe device can be reached in two ways, explicltly with %pipe% ++ or implicitly with "|", so we have to check for both ++ */ ++ char f[gp_file_name_sizeof]; ++ const char *pipestr = "|"; ++ const size_t pipestrlen = strlen(pipestr); ++ const size_t preflen = strlen(iodev->dname); ++ const size_t nlen = strlen(fname); ++ int code1; ++ ++ if (preflen + nlen >= gp_file_name_sizeof) ++ return_error(gs_error_invalidaccess); ++ ++ memcpy(f, iodev->dname, preflen); ++ memcpy(f + preflen, fname, nlen + 1); ++ ++ code1 = gp_validate_path(mem, f, access); ++ ++ memcpy(f, pipestr, pipestrlen); ++ memcpy(f + pipestrlen, fname, nlen + 1); + +- if (gp_validate_path(mem, fname, access) != 0) ++ if (code1 != 0 && gp_validate_path(mem, f, access) != 0 ) + return gs_error_invalidfileaccess; + + /* +diff --git a/base/gp_mshdl.c b/base/gp_mshdl.c +index 2b964ed74..8d87ceadc 100644 +--- a/base/gp_mshdl.c ++++ b/base/gp_mshdl.c +@@ -95,8 +95,17 @@ mswin_handle_fopen(gx_io_device * iodev, const char *fname, const char *access, + long hfile; /* Correct for Win32, may be wrong for Win64 */ + gs_lib_ctx_t *ctx = mem->gs_lib_ctx; + gs_fs_list_t *fs = ctx->core->fs; ++ char f[gp_file_name_sizeof]; ++ const size_t preflen = strlen(iodev->dname); ++ const size_t nlen = strlen(fname); + +- if (gp_validate_path(mem, fname, access) != 0) ++ if (preflen + nlen >= gp_file_name_sizeof) ++ return_error(gs_error_invalidaccess); ++ ++ memcpy(f, iodev->dname, preflen); ++ memcpy(f + preflen, fname, nlen + 1); ++ ++ if (gp_validate_path(mem, f, access) != 0) + return gs_error_invalidfileaccess; + + /* First we try the open_handle method. */ +diff --git a/base/gp_msprn.c b/base/gp_msprn.c +index ed4827968..746a974f7 100644 +--- a/base/gp_msprn.c ++++ b/base/gp_msprn.c +@@ -168,8 +168,16 @@ mswin_printer_fopen(gx_io_device * iodev, const char *fname, const char *access, + uintptr_t *ptid = &((tid_t *)(iodev->state))->tid; + gs_lib_ctx_t *ctx = mem->gs_lib_ctx; + gs_fs_list_t *fs = ctx->core->fs; ++ const size_t preflen = strlen(iodev->dname); ++ const size_t nlen = strlen(fname); + +- if (gp_validate_path(mem, fname, access) != 0) ++ if (preflen + nlen >= gp_file_name_sizeof) ++ return_error(gs_error_invalidaccess); ++ ++ memcpy(pname, iodev->dname, preflen); ++ memcpy(pname + preflen, fname, nlen + 1); ++ ++ if (gp_validate_path(mem, pname, access) != 0) + return gs_error_invalidfileaccess; + + /* First we try the open_printer method. */ +diff --git a/base/gp_os2pr.c b/base/gp_os2pr.c +index f852c71fc..ba54cde66 100644 +--- a/base/gp_os2pr.c ++++ b/base/gp_os2pr.c +@@ -107,9 +107,20 @@ os2_printer_fopen(gx_io_device * iodev, const char *fname, const char *access, + FILE ** pfile, char *rfname, uint rnamelen) + { + os2_printer_t *pr = (os2_printer_t *)iodev->state; +- char driver_name[256]; ++ char driver_name[gp_file_name_sizeof]; + gs_lib_ctx_t *ctx = mem->gs_lib_ctx; + gs_fs_list_t *fs = ctx->core->fs; ++ const size_t preflen = strlen(iodev->dname); ++ const int size_t = strlen(fname); ++ ++ if (preflen + nlen >= gp_file_name_sizeof) ++ return_error(gs_error_invalidaccess); ++ ++ memcpy(driver_name, iodev->dname, preflen); ++ memcpy(driver_name + preflen, fname, nlen + 1); ++ ++ if (gp_validate_path(mem, driver_name, access) != 0) ++ return gs_error_invalidfileaccess; + + /* First we try the open_printer method. */ + /* Note that the loop condition here ensures we don't +diff --git a/base/gslibctx.c b/base/gslibctx.c +index 6dfed6cd5..318039fad 100644 +--- a/base/gslibctx.c ++++ b/base/gslibctx.c +@@ -655,82 +655,39 @@ rewrite_percent_specifiers(char *s) + int + gs_add_outputfile_control_path(gs_memory_t *mem, const char *fname) + { +- char *fp, f[gp_file_name_sizeof]; +- const int pipe = 124; /* ASCII code for '|' */ +- const int len = strlen(fname); +- int i, code; ++ char f[gp_file_name_sizeof]; ++ int code; + + /* Be sure the string copy will fit */ +- if (len >= gp_file_name_sizeof) ++ if (strlen(fname) >= gp_file_name_sizeof) + return gs_error_rangecheck; + strcpy(f, fname); +- fp = f; + /* Try to rewrite any %d (or similar) in the string */ + rewrite_percent_specifiers(f); +- for (i = 0; i < len; i++) { +- if (f[i] == pipe) { +- fp = &f[i + 1]; +- /* Because we potentially have to check file permissions at two levels +- for the output file (gx_device_open_output_file and the low level +- fopen API, if we're using a pipe, we have to add both the full string, +- (including the '|', and just the command to which we pipe - since at +- the pipe_fopen(), the leading '|' has been stripped. +- */ +- code = gs_add_control_path(mem, gs_permit_file_writing, f); +- if (code < 0) +- return code; +- code = gs_add_control_path(mem, gs_permit_file_control, f); +- if (code < 0) +- return code; +- break; +- } +- if (!IS_WHITESPACE(f[i])) +- break; +- } +- code = gs_add_control_path(mem, gs_permit_file_control, fp); ++ ++ code = gs_add_control_path(mem, gs_permit_file_control, f); + if (code < 0) + return code; +- return gs_add_control_path(mem, gs_permit_file_writing, fp); ++ return gs_add_control_path(mem, gs_permit_file_writing, f); + } + + int + gs_remove_outputfile_control_path(gs_memory_t *mem, const char *fname) + { +- char *fp, f[gp_file_name_sizeof]; +- const int pipe = 124; /* ASCII code for '|' */ +- const int len = strlen(fname); +- int i, code; ++ char f[gp_file_name_sizeof]; ++ int code; + + /* Be sure the string copy will fit */ +- if (len >= gp_file_name_sizeof) ++ if (strlen(fname) >= gp_file_name_sizeof) + return gs_error_rangecheck; + strcpy(f, fname); +- fp = f; + /* Try to rewrite any %d (or similar) in the string */ +- for (i = 0; i < len; i++) { +- if (f[i] == pipe) { +- fp = &f[i + 1]; +- /* Because we potentially have to check file permissions at two levels +- for the output file (gx_device_open_output_file and the low level +- fopen API, if we're using a pipe, we have to add both the full string, +- (including the '|', and just the command to which we pipe - since at +- the pipe_fopen(), the leading '|' has been stripped. +- */ +- code = gs_remove_control_path(mem, gs_permit_file_writing, f); +- if (code < 0) +- return code; +- code = gs_remove_control_path(mem, gs_permit_file_control, f); +- if (code < 0) +- return code; +- break; +- } +- if (!IS_WHITESPACE(f[i])) +- break; +- } +- code = gs_remove_control_path(mem, gs_permit_file_control, fp); ++ rewrite_percent_specifiers(f); ++ ++ code = gs_remove_control_path(mem, gs_permit_file_control, f); + if (code < 0) + return code; +- return gs_remove_control_path(mem, gs_permit_file_writing, fp); ++ return gs_remove_control_path(mem, gs_permit_file_writing, f); + } + + int +-- +2.20.1 + diff --git a/package/ghostscript/ghostscript.mk b/package/ghostscript/ghostscript.mk index 5b50c94405..ca24c61678 100644 --- a/package/ghostscript/ghostscript.mk +++ b/package/ghostscript/ghostscript.mk @@ -21,6 +21,9 @@ GHOSTSCRIPT_DEPENDENCIES = \ libpng \ tiff +# 0002-Bug-704342-Include-device-specifier-strings-in-acces.patch +GHOSTSCRIPT_IGNORE_CVES += CVE-2021-3781 + # Ghostscript includes (old) copies of several libraries, delete them. # Inspired by linuxfromscratch: # http://www.linuxfromscratch.org/blfs/view/svn/pst/gs.html -- 2.30.2